I'd start high and work your way down gradually. Reducing fuel in large increments can be expensive, unless you prefer to do it that way. 1 "point" on the BD box = .5% of a "unit" of fuel. Best way to see what something is doing is throw an assload of fuel at an rpm range and see what it does, then slowly back it down until it cleans up.
Check with the manufacturer of your mods, they should be able to give you numbers that put you in the ballpark.